"If more people in the U.S. used LEDs in their homes and businesses, the country's electricity consumption could be cut in half," says Zhichao Hu, Ph.D., a member of the Rutgers University team that performed the research under the direction of Jing Li, Ph.D. At that time, he was a graduate student. He is now a postdoc at Rutgers and is studying the recovery of rare-earth elements there. Zhichao adds that studies show substituting one LED light for a common incandescent light bulb in every American household could save the nation $700 million annually in energy costs.
To achieve the common, soft white light that consumers expect, current LED technologies typically use a single semiconductor chip to produce light, usually blue, and then rely on a yellow-emitting "phosphor" coating to shift the color to white. That's because LEDs do not emit a white light. The phosphor is made from materials, such as cerium-doped yttrium aluminum garnet, that are composed of rare-earth elements. These elements are expensive and in limited supply, since they are primarily available only from mining operations outside the U.S. Additionally, the light output of these phosphors tends to be harsh, "cold" colors.
Read more at: http://phys.org/news/2015-08-technology-energy-greenhouse-gas-emissions.html#jCp